[Liftoff][mips] Optimize i32_set_cond instruction

Optimize implementation of i32_set_cond using new macro-assembler
instruction LoadZeroOnCondition. This way, emitting branches is
avoided.

Bug: v8:6600
Change-Id: Icccb2f3714645851fac68a666ddb33db4a9d8062
Reviewed-on: https://chromium-review.googlesource.com/985976
Commit-Queue: Sreten Kovacevic <sreten.kovacevic@mips.com>
Reviewed-by: Ivica Bogosavljevic <ivica.bogosavljevic@mips.com>
Cr-Commit-Position: refs/heads/master@{#52300}

src/wasm/baseline/mips/liftoff-assembler-mips.h

@@ -622,25 +622,19 @@ void LiftoffAssembler::emit_i32_eqz(Register dst, Register src) {
 
 void LiftoffAssembler::emit_i32_set_cond(Condition cond, Register dst,
                                          Register lhs, Register rhs) {
-  Label true_label;
-  if (dst != lhs && dst != rhs) {
-    ori(dst, zero_reg, 0x1);
+  Register tmp = dst;
+  if (dst == lhs || dst == rhs) {
+    tmp = GetUnusedRegister(kGpReg, LiftoffRegList::ForRegs(lhs, rhs)).gp();
   }
+  // Write 1 as result.
+  TurboAssembler::li(tmp, 1);
 
-  TurboAssembler::Branch(&true_label, cond, lhs, Operand(rhs));
-  // If not true, set on 0.
-  TurboAssembler::mov(dst, zero_reg);
+  // If negative condition is true, write 0 as result.
+  Condition neg_cond = NegateCondition(cond);
+  TurboAssembler::LoadZeroOnCondition(tmp, lhs, Operand(rhs), neg_cond);
 
-  if (dst != lhs && dst != rhs) {
-    bind(&true_label);
-  } else {
-    Label end_label;
-    TurboAssembler::Branch(&end_label);
-    bind(&true_label);
-
-    ori(dst, zero_reg, 0x1);
-    bind(&end_label);
-  }
+  // If tmp != dst, result will be moved.
+  TurboAssembler::Move(dst, tmp);
 }
 
 void LiftoffAssembler::emit_i64_eqz(Register dst, LiftoffRegister src) {

src/wasm/baseline/mips64/liftoff-assembler-mips64.h

@@ -504,25 +504,19 @@ void LiftoffAssembler::emit_i32_eqz(Register dst, Register src) {
 
 void LiftoffAssembler::emit_i32_set_cond(Condition cond, Register dst,
                                          Register lhs, Register rhs) {
-  Label true_label;
-  if (dst != lhs && dst != rhs) {
-    ori(dst, zero_reg, 0x1);
+  Register tmp = dst;
+  if (dst == lhs || dst == rhs) {
+    tmp = GetUnusedRegister(kGpReg, LiftoffRegList::ForRegs(lhs, rhs)).gp();
   }
+  // Write 1 as result.
+  TurboAssembler::li(tmp, 1);
 
-  TurboAssembler::Branch(&true_label, cond, lhs, Operand(rhs));
-  // If not true, set on 0.
-  TurboAssembler::mov(dst, zero_reg);
+  // If negative condition is true, write 0 as result.
+  Condition neg_cond = NegateCondition(cond);
+  TurboAssembler::LoadZeroOnCondition(tmp, lhs, Operand(rhs), neg_cond);
 
-  if (dst != lhs && dst != rhs) {
-    bind(&true_label);
-  } else {
-    Label end_label;
-    TurboAssembler::Branch(&end_label);
-    bind(&true_label);
-
-    ori(dst, zero_reg, 0x1);
-    bind(&end_label);
-  }
+  // If tmp != dst, result will be moved.
+  TurboAssembler::Move(dst, tmp);
 }
 
 void LiftoffAssembler::emit_i64_eqz(Register dst, LiftoffRegister src) {